Fuel control for internal combustion engines



May 31, 1960 A. w. FROGGATT E 2,938,510

FUEL CONTROL FOR INTERNAL COMBUSTION ENGINES Filgd 0011 15, 1957 2 Sheets-Sheet 1 0 4 Z1 Z8 0 [5 w? f if 19 15 o 24 Z6 Z5 0 Z] 6 1; 20 ifi o A I .79 [f [6 Z6 O I] 16. I 22 in 2 f a [9 Z7 15 's- 1 M Wad L @JW May 31, 1960 A. w. FROGGATT ETAL 2,938,510

FUEL CONTROL FOR INTERNAL COMBUSTION ENGINES Filed Oct. 15, 1957 2 Sheets-Sheet 2 FUEL CONTROL FOR INTERNAL COMBUSTION ENGINES Alfred W. Froggatt and George L. Parsons, Lincoln,

England, assignors to Boston & Hornsby Limited, Lincoln, England, a company of Great Britain Filed Oct. 15, 1957, Ser. No. 690,387

Claims priority, application Great Britain Nov. 3, 1956 1 Claim. (Cl. 123-140) This invention relates to an equipment for controlling the delivery of fuel to an internal combustion engine, and more particularly though perhaps not exclusively to such equipment applied to a compression ignition or socalled diesel engine.

One of the objects of the invention is to provide during normal running a maximum fuel stop limiting the amount of overload which can be carried by the engine to a predetermined value, this being usually the one hour rating; and at the same time to provide an automatic means of obtaining a specific quantity of fuel in excess of this limited amount for starting purposes.

Another object of the invention is to provide such an automatic means of applying an excess quantity of fuel during starting that it cannot be deliberately or inadvertently left in operation once normal running is started; it is known to engine makers that some users have been in the habit of fixing the excess fuel delivery means to suit some convenience of their own but with an inevitable detriment to the engine.

The following description relates to the drawings accompanying the provisional specification which show by way of example only two embodiments of the invention.

In the drawings:

Figure 1 is a diagrammatic view of an engine fuel pump with its control mechanism and associated governor, the parts being in the normal-running governorcontrolled positions;

Figure 2 is a view similar to that of Figure 1, but with the parts in the maximum load positions;

Figure 3 is a view similar to those of Figures 1 and 2, but with the parts in the starting positions; and

Figure 4 is a diagrammatic view of a second embodiment of the invention.

Referring to Figures 1, 2 and 3, the known type of fuel pump 11 delivers fuel through pipe 12 to an injector not shown. The quantity of fuel so delivered is determined by the positioning of a control rack 13 which increases the delivery as it moves to the right. A light spring 14 urges the control rack 13 towards the right, this movement being limited by engagement of the right hand end of the rack 13 with the left hand end of an aligned push rod 15. A governor comprising governor weights 16 is rotated at a speed related to the engine speed, say twice the engine speed, and tends as the engine speed increases and the weights fly outwards, to urge the push rod 15 to the left as indicated by the arrow P. The push rod 15 is supported within a bush 17 screwed into the governor casing 18 and forming a limiting abutment against the rightward movement as will appear. On a narrowed part 19 of the push rod 15 is a collar 20 mounted so as to be freely slidable until met on the right hand by the shoulder 21 and on the left hand by a circlip 22. A main governor spring hired States Patent@ 23 acts upon a governor lever 24, tending to turn it anticlockwise and hence, by engagement of the lower lever end with the flange collar 20, to force the collar 20 and push rod 15 to the right.

In the condition of governor-controlled normal-rum ning as shown in Figure l, the collar 20 abuts the shoulder 21 and the system is floating, that is to say the leftward force P developed by the governor weights is just balanced by the combined forces of the rightward acting springs 14 and 23.

As the load on the engine is increased and the speed tends to fall, the force P decreases and the push rod 15 moves to the right, followed by the control rack 13 under the influence of its spring 14, until a new equilibrium point is reached.

This rightward, fuel increasing, movement is limited by a stop 17 which is set on test to give the maximum load at which the engine is intended to operate (usually 10% above normal British Standards Institution 12-hour rating). In this limiting condition, shown in Figure 2, the combined force of springs 14 and 23 is equal to or greater than force P and the collar 20 is in contact with stop 17.

The force from spring 14 alone is not suflicient to overcome P and produce any further movement of the control rack to provide more fuel.

However, when the engine is to be started, a yet greater delivery of fuel is necessary. At this time, the engine being stationary and the force P being zero, the spring 14 is sufiicient to push the control rack 13 and the push rod 15 to the right until the circlip 22 comm into contact with the back of the collar 20 thus limiting the amount of excess fuel available for starting. The rack 13 will remain in this position until the engine speed rises sufliciently for the force P to overcome the spring 14. The spring 14 is so designed that the speed at which this occurs lies between the starting speed (hand or motor) and the minimum idling speed of the engine.

In Figure 4, the invention is shown applied to a governor and fuel pump of the so-called Monobloc type. So far as practicable the same reference numerals are used as with respect to Figures 1 to 3. In this case however, the push rod 15 is replaced functionally by the sleeve 25, and circlip 22 is replaced by a cap 26, while the further lever 27 is introduced between the governor element and the fuel pump control rack 13.

The equivalent of the bush 17 in Figure 1 for limiting movement of the collar 20 is the screwed stop 23 limiting the travel of the governor lever 24. The functioning of the device will be evident from what has gone before.

What we claim is:

An equipment for controlling the delivery of fuel to an internal combustion engine comprising a fixed supporting member; a fuel supply valve having a controlling member displaceable relative to said fixed supporting member; a light spring urging said fuel controlling member towards its maximum fuel supply position; a force transmitting member connected to move said fuel controlling member in fuel-increasing direction and capable of limited displacement relative thereto; a strong spring urging said force-transmitting member towards its maximum fuel supply position; said springs acting upon said controlling member independently of each other; a centrifugal governor sensitive to the speed of the engine to be controlled and connected to urge said fuel controlling member towards its minimum fuel supply position when the engine is running; and a stop on said fixed supporti 3 ing member engaged by said force-transmitting member at a point of maximum desirable fuel supply for normal running of said engine; said fuel controlling member being further movable to a greater fuel supply position under the action of said light spring after said force- 6 transmitting member reaches said stop, the force of said light spring upon said controlling member being insutficient to cause said further movement at normal idling speed of said governor.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Great Britain Feb. 22, 1946 

